In a process of manufacturing a semiconductor device, an LCD substrate, or the like, a resist liquid is applied to a surface of a substrate, e.g., a semiconductor wafer (hereinafter, referred to as “wafer”), exposed, and then, developed, so as to form a resist pattern as a pattern mask on the wafer surface. In the related art, it has been well known that a surface of the resist pattern has fine unevenness, which may unfavorably influence a pattern line width when an etching process is performed as a subsequent process. Accordingly, a smoothing process for improving a roughness of the pattern line width (LWR: Line Width Roughness) of the resist pattern has been proposed.
The smoothing process is performed, for example, by forming a solvent vapor atmosphere for dissolving the resist in a processing chamber, exposing the resist pattern to such an atmosphere, and dissolving a surface layer of the resist pattern. Accordingly, the surface layer is dissolved by the solvent and planarized, and the pattern surface roughness is improved to correct a pattern shape.
However, in the smoothing process, the resist pattern may be excessively dissolved by the solvent, and thereby breaking the resist pattern, when a try to increase an improvement rate of the LWR is made with respect to, e.g., a resist pattern containing a frail portion. To address this, the related art discloses a method in which the roughness is uniformly improved in a wafer surface by independently using both a process of evacuating surroundings of a wafer and a process of forming a temperature gradient having a higher temperature at a central portion of the wafer surface. In this case, however, throughput may be adversely affected due to repetition of the dissolving and the drying the resist pattern surface. In addition, a more enhanced method which can suppress the breakdown of the resist pattern has been required.